①+②=2x²-2
=2(x²-1)
=2(x+1)(x-1)
①+③=2x²-4x+2
=2(x²-2x+1)
=(x-1)²
②+③=2x²-8x
=2x(x-4)再帮我一题分式因解计算题750²-250²750²-250²=(750+250)(750-250)=1000×500=500000